Why GitOps with ArgoCD in Kubernetes? - Purpose & Use Cases

The Big Idea

What if you could update your entire app fleet just by pushing code to Git?

The Scenario

Imagine you have to update your app on many servers by logging into each one and typing commands manually.

You write down what you did on a sticky note, but it's easy to forget steps or make mistakes.

The Problem

Manual updates take a lot of time and are easy to mess up.

If you forget a step or type a wrong command, your app might break.

It's hard to keep track of what changed and fix problems quickly.

The Solution

GitOps with ArgoCD lets you store your app setup in Git, like a safe notebook.

ArgoCD watches Git and automatically updates your app to match what's in the notebook.

This means updates are fast, consistent, and easy to track.

Before vs After

✗ Before

ssh server1
kubectl apply -f app.yaml
ssh server2
kubectl apply -f app.yaml

✓ After

git commit -am 'update app'
git push
# ArgoCD syncs automatically

What It Enables

You can manage app updates safely and automatically across many servers just by changing files in Git.

Real Life Example

A team uses GitOps with ArgoCD to deploy new app versions instantly to hundreds of servers without logging into each one.

Key Takeaways

Manual updates are slow and risky.

GitOps stores app setup in Git for safe tracking.

ArgoCD automates updates to keep apps in sync with Git.

Practice

1. What is the main purpose of using ArgoCD in a Kubernetes environment with GitOps?

easy

A. To replace Kubernetes with a new container orchestration system

B. To manually deploy applications without using Git

C. To store container images in a private registry

D. To automatically sync Kubernetes cluster state with Git repository configurations

Solution

1. Step 1: Understand GitOps concept

   GitOps uses Git as the single source of truth for application configurations.

2. Step 2: Role of ArgoCD in GitOps

   ArgoCD automatically syncs Kubernetes cluster state to match the Git repo, ensuring deployments are consistent and automated.

3. Final Answer:

   To automatically sync Kubernetes cluster state with Git repository configurations -> Option D

4. Quick Check:

   GitOps = Auto-sync cluster with Git [OK]

Hint: Remember: ArgoCD syncs cluster state from Git automatically [OK]

Common Mistakes:

• Thinking ArgoCD replaces Kubernetes
• Believing ArgoCD deploys apps manually
• Confusing ArgoCD with container registries

2. Which of the following is the correct ArgoCD CLI command to create an application named myapp syncing from Git repo https://github.com/example/repo.git with path k8s and target cluster https://kubernetes.default.svc?

easy

A. argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default

B. argocd create app myapp --repository https://github.com/example/repo.git --directory k8s --cluster https://kubernetes.default.svc

C. kubectl create app myapp --repo https://github.com/example/repo.git --path k8s

D. argocd app new myapp --repo-url https://github.com/example/repo.git --folder k8s --server https://kubernetes.default.svc

Solution

1. Step 1: Identify correct ArgoCD CLI syntax

   The correct command uses argocd app create with flags --repo, --path, --dest-server, and --dest-namespace.

2. Step 2: Compare options

   argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default matches the official syntax exactly. Others use incorrect commands or flags.

3. Final Answer:

   argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default -> Option A

4. Quick Check:

   Correct CLI syntax = argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default [OK]

Hint: Remember: 'argocd app create' plus repo, path, dest-server flags [OK]

Common Mistakes:

• Using kubectl instead of argocd CLI
• Wrong flag names like --repository or --folder
• Incorrect command order or missing --dest-namespace

3. Given the following ArgoCD Application YAML snippet, what will happen when ArgoCD syncs this app?

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: sample-app
spec:
  source:
    repoURL: https://github.com/example/app-configs.git
    path: production
  destination:
    server: https://kubernetes.default.svc
    namespace: default
  syncPolicy:
    automated: {}

medium

A. ArgoCD will reject the app because syncPolicy is empty

B. ArgoCD will only show the app status but not deploy it automatically

C. ArgoCD will automatically deploy and keep the app in sync with the Git repo

D. ArgoCD will deploy the app once but not update it on Git changes

Solution

1. Step 1: Understand syncPolicy automated

   The syncPolicy: automated: {} means ArgoCD will auto-sync changes from Git to cluster.

2. Step 2: Effect on deployment

   ArgoCD will deploy the app initially and keep it updated automatically when Git changes.

3. Final Answer:

   ArgoCD will automatically deploy and keep the app in sync with the Git repo -> Option C

4. Quick Check:

   syncPolicy automated = auto deploy and sync [OK]

Hint: syncPolicy automated means auto deploy and keep in sync [OK]

Common Mistakes:

• Thinking empty braces mean no automation
• Assuming manual sync is required
• Confusing syncPolicy with app rejection

4. You created an ArgoCD app but it shows OutOfSync status even after you committed changes to Git. Which of the following is the most likely cause?

medium

A. The app's syncPolicy is not set to automated, so manual sync is needed

B. The Git repository URL is incorrect and unreachable

C. The Kubernetes cluster is down and cannot apply changes

D. The app name in ArgoCD does not match the Git repo name

Solution

1. Step 1: Understand OutOfSync status

   OutOfSync means cluster state differs from Git repo state.

2. Step 2: Check syncPolicy effect

   If syncPolicy is not automated, ArgoCD won't auto-apply changes; manual sync is required.

3. Final Answer:

   The app's syncPolicy is not set to automated, so manual sync is needed -> Option A

4. Quick Check:

   OutOfSync + no automated sync = manual sync needed [OK]

Hint: OutOfSync often means no automated sync set [OK]

Common Mistakes:

• Assuming cluster is down without checking
• Blaming Git URL without error evidence
• Thinking app name mismatch causes OutOfSync

5. You want to ensure that ArgoCD only deploys changes to your Kubernetes cluster after manual approval, but still track changes in Git automatically. Which configuration should you use in your ArgoCD Application YAML?

hard

A. Set syncPolicy: automated: {} to enable auto deploy

B. Omit syncPolicy and use manual sync to approve changes

C. Set syncPolicy: automated: null to disable auto deploy

D. Set syncPolicy: automated: { prune: true, selfHeal: true } for auto deploy with cleanup

Solution

1. Step 1: Understand manual approval need

   To require manual approval before deployment, auto sync must be disabled.

2. Step 2: Configure syncPolicy accordingly

   Omitting syncPolicy disables auto sync, so ArgoCD tracks Git but waits for manual sync.

3. Final Answer:

   Omit syncPolicy and use manual sync to approve changes -> Option B

4. Quick Check:

   No syncPolicy = manual approval required [OK]

Hint: No syncPolicy means manual sync only [OK]

Common Mistakes:

• Using automated sync disables manual approval
• Setting automated with prune/selfHeal still auto deploys
• Setting automated: null is invalid syntax